9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The INA183 measures the voltage developed across a current-sensing resistor when current passes through it.

The ability to drive the reference pin to adjust the functionality of the output signal offers multiple configurations,

as discussed throughout this section.

9.1.1 RSENSE and Device Gain Selection

Choosing the largest possible shunt resistor will maximize the accuracy of any current-sense amplifier. A large

sense resistor maximizes the differential input signal for a given amount of current flow and reduces the error

contribution of the offset voltage. However, there are practical limits as to how large the current-sense resistor

can be in a given application because of the resistor size and maximum allowable power dissipation. Equation 1

gives the maximum value for the current-sense resistor for a given power dissipation budget:

MAX

SENSE

2

MAX

PD

R

I

(1)

where:

• PDMAX is the maximum allowable power dissipation in RSENSE.

• IMAX is the maximum current expected to flow through RSENSE.

An additional limitation on the size of the current-sense resistor and device gain is due to the power-supply

voltage at the IN+ pin, and device swing-to-rail limitations. To ensure that the current-sense signal is properly

passed to the output, both positive and negative output swing limitations must be examined. Equation 2 provides

the maximum values of RSENSE and GAIN to keep the device from exceeding the positive swing limitation.

I

MAX

ª RSENSE ª *$,1 < VSP

(2)

where:

• IMAX is the maximum current that will flow through RSENSE.

• GAIN is the gain of the current-sense amplifier.

• VSP is the positive output swing as specified in the data sheet.

Positive output swing limitations should be considered when selecting the value of RSENSE. There is always a

trade-off between the value of the sense resistor and the gain of the device under consideration. If the sense

resistor selected for the maximum power dissipation is too large, then it is possible to select a lower-gain device

to avoid positive swing limitations.

INA183

SBOSA08 – FEBRUARY 2021

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